diff --git a/pyproject.toml b/pyproject.toml
index 51c4ec8..6275187 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
 ]
 dependencies = [
-    "empack>=4.0.2,<5",
+    "empack>=4.0.2,<6",
     "traitlets",
     "jupyterlite-core>=0.1,<0.5",
     "pyyaml",